The present invention relates to a coffee grinding apparatus which produces a selected weight of ground coffee.
A variety of coffee grinding apparatus are available which weigh a quantity of whole coffee beans to be ground or which measure a desired quantity of whole coffee beans as a function of time. For example, U.S. Pat. No. 4,789,106 to Weber, issued Dec. 6, 1988, provides a grinding apparatus having a pair of hoppers in a gravity feed relationship with a grinding mechanism. Whole coffee beans are dispensed from the hoppers onto a bean bucket which mechanically weighs the whole beans prior to grinding. When a quantity of whole beans has accumulated on the bean bucket, the bean bucket tips and drops the whole beans into the grinding mechanism.
A problem with the device as shown in Weber, and other devices of this type, is that the beans are weighed in the whole coffee bean form prior to grinding and therefore cannot compensate for the size, density, oiliness and other characteristics of the beans. It is important to consider these characteristics in measuring ground coffee since these characteristics affect the weight of the ground coffee.
In producing brewed beverages it is important to maintain the consistency of the flavor of beverages produced by the brewing machine. Customers appreciate a predictably good tasting cup of coffee. A key factor in maintaining consistency in brewing beverages is maintaining the proper amount of ground coffee used in the infusion process. Maintaining the proper amount of coffee is also important to coffee vendors to economically manage and efficiently utilize ground coffee. The flavor of a brewed beverage such as coffee may require maintaining a tolerance for the measurement of the ground coffee within +/-0.1 ounce. Such precise measurement tolerances require highly accurate measuring controls.
With regard to the device in Weber, the device measures whole beans and therefore may not be able to maintain the +/-0.1 ounce weighing tolerance. The device in Weber allows beans to flow from a hopper until a predetermined weight is sensed by the bean bucket. When the predetermined weight of whole beans is sensed, a hopper gate between the hopper and bean bucket is closed. In view of the beans being in a whole bean state, the measurement may be inaccurate since numerous whole beans may be dispensed from the hopper after the desired weight is sensed. The problem of measuring beans using a device as shown in Weber is exacerbated when the whole beans have an oily characteristic such as is found in dark roast beans, especially, french or espresso roast beans. The oiler beans tend to cling to each other thereby almost assuring an inaccurate measurement.
Another problem with accurately weighing ground coffee is that many coffee grinding apparatus which combine a storage hopper and a dispensing mechanism rely on volume based measurement to dispense a weight of coffee beans. For instance, in a device combining a storage hopper with an auger to dispense beans from the hopper, the grinding device will dispense a predetermined volume of coffee to be ground, in contrast to traditional coffee measuring methods in which coffee is measured by weight. When beans are of a consistent density, a timed or volume measuring mechanism will generally yield a fairly accurate weight measurement. In reality, coffee beans often vary in density due to variations in the type of bean, the roast of the bean, and/or blending. These variations may occur even within a single brand or type of coffee. Such measuring and grinding apparatus may not achieve the desired tolerance where precision weight control is required.
In view of the foregoing problems and requirements, there is a need for a grinding apparatus which precisely dispenses a desired weight of ground coffee regardless of the characteristics of the whole coffee beans being ground.